Building a Retro Synthesizer With the Pocket Mini Computer

This Instructable will show you how to create a "retro sounding" synthesizer using your Pocket Mini Computer.

I'm a huge fan of the Commodore 64. One of it's most memorable characteristics is the sound of it's 3 voice SID chip. Most Xgeners will recognize it's unique sound from old school videos games like Commando or MULE. The Pocket Mini Computer has access to an excellent emulation of the SID chip, called SIDcog, used extensively in this project.

Ready to rock out with a SID Synth? Read on!

Requirements:

The Pocket Mini Computer (see next page for details)

Breadboard or "perf" board.

2 - 220ohm resistors

1 - 4.7k resistors

1 - 6N138 Optocoupler

1 - 1N914 Signal Diode

I've included schematics and links to all sources so you can build and expand on this project to your hearts content.

Supplies:

Step 1: What Is the Pocket Mini Computer?

You might be scratching your head at the requirement of a Pocket Mini Computer.

What's a Pocket Mini Computer? I'm glad you asked!

The Pocket Mini Computer is an open source "mini computer" design which uses the Parallax Propeller microcontroller as it's brain. The kit from Propellerpowered.com comes pre-loaded with a retro-style BASIC. The hardware itself is extremely powerful & featured.

More details about the Pocket Mini Computer can be found on this Wiki.
Schematics and Souce Code are avaible for anyone who wants to "roll their own".

Step 2: MIDI-IN Schematic

The MIDI-IN circuit is simple and surprising easy to assemble.

The MIDI communications protocol is a type of slower, serial communication easily understood by the microcontroller. (The full "geeky" details of MIDI communication can be found here: http://en.wikipedia.org/wiki/MIDI. It's a recommended read.)

Step 3: Loading SIDSynth

Once you've attached the MIDI circuit to P12 of your Pocket Mini Computer, you are ready to play.

Download a copy of the SIDSYNTH.BIN binary and copy it to your microSD card.

Use the BASIC command:

LOAD "SIDSYNTH.BIN"

You will hear a couple clicks from the speaker as the program initializes. The screen will clear and you are ready to jam.

Waveform, Attack, Decay, and Sustain are controllable using the first four knobs or controls on your keyboard. (varies from keyboard to keyboard)

You can also switch instruments to various great presets just as you would with a typical electric piano.

Step 4: About the SIDSynth Software

The magic behind this Instructable lies in two MIT licensed objects used by the Propeller chip:

SIDcog written by Johannes Ahlebrand
SIDcog is an emulation of the Commodore 64 SID chip for the Parallax Propeller. Details about this program can be found in this forum thread. Complete source code is provided as well.

Polyphonic SIDSynth written by Alessandro De Luca.
Polyphonic SIDSynth takes advantage of the SIDcog software and StereoSpatializer written by Chip Gracey. Details about this program can be found in this forum thread. Complete source code is provided as well.

Without these two objects, this project simply wouldn't be possible.

Thank you to Johannes and Alessandro!

Compiling the Polyphonic SIDSynth on your own requires the use of Brad's Spin Tool, as it uses some features not supported in the Parallax Spin Tool. There are several options for various configurations including the use of a USB based midi keyboard, and SPDIG Audio output.

Step 5: Extra: SIDPLAYER

Something EXTRA!

If you watched the video in the first step of this Instructable, you saw me show off the capabilities of SIDcog with a SIDplayer program.

Arduino Contest 2019

Classroom Science Contest

Colors of the Rainbow Contest

4 Discussions

I'm curious if there is any schematics/kits for using a real sid chip in this kit? I'm looking for an affordable diy sid project. *Nicholas Faith @ Gmail .com* (remove spaces between "*") I'm looking to brush up on my skills while building self contained sid synth that is fully programmable with display, matrix grid et al. thanks

i found it a little commercial-ish but the project is still pretty good and the kit is reasonably priced considering it includes the quickstart board .. very tempting to buy

if i'm not mistaken, i think this could be done with just the quickstart board and midi optoisolator circuit right? you would just have to load the sidsynth on before hand... or am i wrong? i haven't worked with the board.